1. Field of the Disclosure
The present disclosure relates to an in-vehicle electronic device which is mounted on a glass surface of a window of a vehicle on which an antenna radiation conductor is arranged to thereby be used, and more particularly to, a case structure of an in-vehicle electronic device which stores, within a holding case, a circuit board in which a preamplifier circuit connected with the antenna radiation conductor, and the like is provided.
2. Description of the Related Art
In the related art, techniques in which a glass surface of a window of a vehicle (for example, a rear window) is used as a disposition space of an antenna radiation conductor are widely known, and these are becoming widespread along with switch to terrestrial digital television broadcasting.
However, signal waves for terrestrial digital broadcasting and the like are required to rapidly amplify a signal received by the antenna radiation conductor, so that excellent reception sensitivity may be obtained by minimizing the attenuation of the received signal. Therefore, in an antenna device in which an antenna radiation conductor is arranged on a glass surface of a window of a vehicle, typically, an electronic device including a built-in circuit board in which a preamplifier circuit is provided is made close to the antenna radiation conductor to thereby be mounted on the same glass surface, so that a foreign signal is transmitted to a reception circuit, and the like via the preamplifier circuit.
In other words, in this kind of electronic device, a circuit board on which an electronic circuit including a preamplifier circuit is provided to mount a connector, a mounting base fixed to a glass surface of a window of a vehicle so that the circuit board is placed and fixed on the mounting base, a connection terminal that enables a feeding electrode and a ground electrode of the electronic circuit to be electrically connected with a pair of feeding units of the antenna radiation conductor, and the like are provided. A foreign signal amplified by this kind of electronic device is transmitted, via a signal cable connected to a connector, to a reception circuit, and the like which are installed in another location of the vehicle, so that a television broadcast, and the like may be viewed through an in-vehicle display device.
In this manner, in an electronic device which is used after being mounted on a glass surface of a window of a vehicle, adjustment of the electronic circuit, the replacement of a part, or the like is efficiently carried out when the circuit board is removed from the glass surface, so that it is easy to perform repair and maintenance of the electronic device even after it has been mounted on the glass surface, thereby providing convenience. Therefore, in the related art, there has been suggested an in-vehicle electronic device in which a mounting base to which an insert nut is attached is adhered and fixed to a glass surface of a window of a vehicle, and a mounting screw that penetrates through the circuit board is screwed to a corresponding insert nut, so that the circuit board is fastened and fixed on the mounting base, and a pair of connection terminals is interposed between the circuit board and the mounting base (for example, see Japanese Unexamined Patent Application Publication No. 2010-132216). In the in-vehicle electronic device in the related art, by unscrewing the mounting screw, it is possible to remove the circuit board from the mounting base fixed to the glass surface.
However, as in the above-described example of the related art, in an in-vehicle electronic device in which a circuit board is fastened and fixed to a mounting base by a mounting screw, there is a problem in that it is difficult to smoothly perform removal of the circuit board when the mounting position of the electronic device with respect to the glass surface of the window of the vehicle is not suitable for screwing and unscrewing the mounting screw. In other words, the mounting base of this kind of electronic device is generally fixed to the edge of a glass surface of a window of a vehicle; however, there are cases where there is a limitation due to the in-vehicle layout near the head of the mounting screw, and it is not possible to secure the operational space required to unscrew the mounting screw using a tool such as a screwdriver. In addition, if the mounting position of the electronic device with respect to the glass surface of the window of the vehicle is limited to a certain extent in order to avoid this situation, there is a problem in that the arrangement position of the antenna radiation conductor is limited as a result.